Cold water is not as good for hydration as room temperature. The theory is that the cold water causes the blood vessels surrounding stomach to shrink, slowing absorption.
One theory, upon which medical researchers have varying opinions regards whether drinking cold water is as good for you as drinking tepid water, particularly when you are exercising. Some doctors suggest that room temperature or body temperature water is better than cold water, because the body has to expend energy to heat cold water to body temperature, resulting in some water loss. On the other hand, some doctors say that after physical exertion, you should drink cold water since it will help cool the body more effectively than room temperature water.
What is clear is most people who drink cold water are likely to consume more of it, since it tends to taste better and is more satisfying. Even if drinking cold water results in marginal water loss, the extra water you will probably drink will help make up for this.
The problem is that as the COLD drinks pass through our system, they solidify the fats from the foods we have just eaten or are eating at present. This makes it challenging for the body to digest and disperse the unwanted fats from our body.
However, if we simply swap our cold drinks for a warm drink (warm water/ coffee/tea/herbals) the warm fluids help the fats in our foods to remain fluid and so easing the digestive system and helping the fats pass through our body (and reduce risk of clogged arteries).
If you are attempting to help bring down a fever, or assist someone with sunstroke (animal or person), you should not immerse that person or animal in cold water. Instead you should use lukewarm water, or even slightly warm water. Cold water can provoke chills, which may actually raise body temperature. Though baths can be a helpful way to bring down high fevers, you especially want to avoid allowing someone to shiver or get chilled. If people with fevers drink cold water that is very icy, they may also get chilly, so lukewarm or tepid water may be a better choice.
There are a number of other urban legends associated with the amount of liquids and the type of liquids you consume. For instance people are told that coffee, tea and sodas deplete water from their bodies. Actually, people who routinely drink caffeinated beverages retain about two-thirds of what they drink, and this can be counted as part of daily fluid intake. Another “myth” regarding water is the eight, eight ounce (.24 l) glasses of water are needed daily. While this amount of water, whether you drink cold water or hot, won’t hurt you, daily intake of food usually provides about half the amount of needed fluids. Most people would get by with drinking about 32 ounces (approx. 1 liter) daily.
Also warm/hot water relaxes the body better. Cold water might be more refreshing, but it may disrupt your vocal cords, that’s why singers always drink room temperature water.
The best indicator on whether your body is getting enough water is urine color. If your urine is dark yellow, chances are you’re not getting enough water. If you pass clear to very light colored yellow urine, your fluid intake is adequate. Remember that urine color in the morning will always be a little darker.